Antimicrobial laundry sour composition



United States Patent ANTIMICROBIAL LAUNDRY SOUR COWOSETION Rodney A. Blomfield, Southgate, and John J. Crarner,

Wyandotte, Mich, assignors to Wyandotte Chemicals Corporation, Wyandotte, Mich, a corporation of Michigan No Drawing. Filed Sept. 20, 1961, Ser. No. 13?,350 4 Claims. (Cl. 252136) This invention relates to an improved germicidal composition. More particularly, it relates to antimicrobial laundry sours containing a mixture of sodium pentachlorophenate and 3,4,4-trichlorocarbanilide which is synergistically active.

Laundry sours have long been used in the laundry industry as a-means for neutralizing alkalinity retained by the load from the washing process. In addition to neutralizing alkalinity, laundry sours are also effective in decomposing any oxidizing bleach left in the fabrics, dissolving stain-forming compounds and preventing starc'hed goods from yellowing when ironed.

In general, the souring step is the last operation in the sequence of operations that constitute the usual washing formulas, hence, this step affords an excellent opportunity to introduce germicidal compounds to the wash load. Heretofore, various germicides have been incorporated into laundry sours so as to render the wash load sterile and free from bacterial or fungal contamination. Unfortunately, tests have shown that most of the germicides employed in conjunction with laundry sours give little germicidal protection and have no lasting effect. Certain other germicides, while very efiective, have not met with commercial success due to their high costs.

It is an object of this invention, therefore, to provide a germicidal composition which is an extremely effective antimicrobial agent and which has a lasting effect. A further object is to provide a composition which is low in cost and readily available. 7

These objects and others have been accomplished in this invention by the discovery of a synergistic combination of sodium pentachlorophenate and 3,4,4-trichlorocarbanilide. Although both of the above named compounds are recognized germicides and have been used separately in various industries, their. use in combination, due to a synergistic effect, is much more effective than each of them used alone and in the same proportion.

The synergistic mixture of sodium pentachlorophenate and 3,4,4'-trichlorocarbanilide can be used alone, or in combination with other compounds. In either event, the preferred mixture comprises about 58 to 93 weight percent of sodium pentachlorophenate and about 42 to 7 weight percent of 3,4,4'-trichlorocarbanilide, the weight percent being based on the weight of the mixture.

The above synergistic mixture is especially effective when used on fabrics to combat air-borne staph and to render the fabric resistant to mildew organisms.

A convenient method of treating fabrics with the synergistic mixture of this invention is to combine the mixture with a laundry sour. Good results have been obtained when the mixture has been combined with any of the following laundry sours: acetic acid, glycolic acid, oxalic acid, ammonium acid fluoride, ammonium silicofluorid-e, sodium acid fluoride, sodium silicofluoride and zinc silicofluoride. When the synergistic mixture is combined with a laundry sour the resulting antimicrobial laundry sour should contain from 10 to 60 weight percent of the synergistic mixture. Sodium pentachlorophenate and 3,4,4'-trichlorocarbanilide are solid compounds and can be obtained in the form of powder, pellets or briquettes. Because these compounds are not soluble in acid media, it is necessary, when combining the synergistic mixture of this invention with a liquid laundry sour such as acetic acid, a

to absorb the liquid acid on a solid carrier. The synergistic mixture can then be blended with the carrier to form a stable antimicrobial laundry sour. While many substances could be used as the carrier, it is preferred to use finely divided, highly porous siliceous compositions which have a pH from about mildly alkaline to slightly acid. Examples of such finely divided, highly porous siliceous compositions include silica gel, diatomaceous earth, fullers earth, bentonite, finely divided silica, synthetic calcium silicate and mixtures thereof. Although naturally occurring siliceous compositions give good results when employed as a carrier, synthetic silicates are preferred because of the economical advantages which accrue due to their use, since smaller amounts of the synthetic silicates can be used to produce comparable results.

When it is desired to produce an antimicrobial laundry sour composition comprising the synergistic mixture of this invention and a liquid laundry sour, the liquid laundry sour is first blended with one of the aforementioned carriers. It has been found that blends containing 50 weight percent of the liquid laundry sour and 50 weight percent of the carrier form a free-flowing powder which is ideally suited for further blending with the synergistic mixture of this invention. However, the particular composition of the blend of laundry sour and carrier is dependent on the sour and carrier used and, hence, can vary over a wide range.

It has also been found that certain antimicrobial laundry sours comprising the synergistic mixture of this invention and powdered or pellet form laundry sours tend to be dusty and thus slightly inconvenient to handle. To overcome this, a small amount of an aliphatic hydrocarbon oil can be added to the mixture. Usually, 1 weight percent or less of oil eliminates any dusting. Since the oil is present in such a small amount and takes no part in the neutralizing or germicidal action any good light viscosity hydrocarbon oil may be used. Examples of such oils are Carnation Oil, manufactured by L. Sonneborn Sons, Inc., having a specific gravity at 60 F. of 0.835/0.845 and a 355 F. flash point, and Base Oil No. 2 manufactured by Phillips Petroleum Company, having a specific gravity at 60 F. of 0.785 and a 210 F. flash point.

The synergistic mixture of this invention can be brought into contact with a fabric by adding it directly to the rinse cycle in a conventional laundry operation or it can be incorporated with a laundry sour and added during the souring step of the laundry cycle. The amount of the synergistic mixture which must be added to the fabric in order to achieve effective results can vary within wide limits and good results are obtained when the concentration of the synergistic mixture is in the range of 0.01 to 0.2 weight percent based upon the weight of the fabric. The preferred concentration, however, is in the range of 0.015 to 0.1 weight percent based upon the weight of the fabric.

The fabrics, which are to be treated in accordance with the method of this invention, should be in contact with the synergistic mixture for about 3 to 15 minutes. Al-

though time of treatment is not critical, it should be of suflicient duration to insure ample opportunity for all the fabric to come into contact with the germicide. For effective results, the synergistic mixture should be employed in an aqueous media which is at a temperature from about 50 F. to 150 F. and at a pH from about 3.5 to 8.5.

The synergistic effect of certain mixtures of sodium pentachlorophenate and 3,4,4'-trichlorocarbanilide can be readily understood by reference to the following tests. The weight percent of sodium pentachlorophenate and 3,4,4-trichlorocarbanilide as shown in the following tables is the weight percent based on the weight of the synergistic mixture,

The FDA froth referred to in the following examples is a standard nutrient solution. The composition of the FDA broth consists of 5 grams of Bacto beef extract, grams of Bacto Peptamin which is a peptic digest of animal tissue, 5 grams of sodium chloride and 1,000 ml. of distilled water. The pH of the FDA broth is 6.8. The above mentioned Bacto compounds are the products of Difco Laboratories Inc., of Detroit, Michigan. The composition of FDA broth was published by the United States Department of Agriculture in their Circular No. 198, dated December 1931. The composition and a discussion of FDA broth may also be found on page 112 of the :text, Antiseptics, Disinfectants, Fungicides and Sterilization, edited by George F. Reddish, published by Lea and Febiger, Philadelphia, 1954.

EXAMPLE 1 100 cubic centimeters of an aqueous antimicrobial sour solution consisting of water, 0.0172 gram of sodium silicofluoride and 0.0086 gram of a mixture of sodium pentachlorophenate (C Cl ON and 3,4,4'-trichlorocarban-ilide (C H Cl N O) were placed in a Launder-Ometer jar containing fifteen fivinch stainless steel balls. 14 grams of muslin cloth were cut into A-inch square swatches and added to the 100 cc. of sour solution. This solution was heated to a temperature of 100 F, and the solution thenagitated for a period of 7 minutes. At the end of this time the swatches were removed from the Launder- Ometer jar and hand squeezed to remove the excess water. The swatches were then pressed dry.

To test the effectiveness of the antimicrobial sour against Staphylococcus aureus bacteria, a swatch, treated with the antimicrobial sour as described above, Was added to a 13 mm. ID. test tube containing 10 cc. of FDA broth plus 2 drops of a 24-hour Staphylococcus aureus, strain 209, broth culture. The test tube was then maintained at a temperature of 90 F. for a 48-hour period. At the end of this period the bacteriostatic effectiveness of the antimicrobial sour was determined by comparing the turbidity of the broth as against uninoculated FDA broth by the use of a Klett-Summerson Photoelectric Colorimeter with a green filter. The results of the above test are shown in the following table and are reported as percent of light transmission relative to the light transmission through uninoculated FDA broth. The lower the percentage of light transmission, the poorer the bacteriostatic effectiveness.

It Will be noted from the data in Table 1 that mixtures of sodium pentac-hlorophenate and 3,4,4'-trichlorocarbanilide consisting of 65.0 to 88.0 and 35.0 to 12.0 weight percent of sodium pentochlorophenate and 3,4,4-trichlorocarbanilide, respectively, based on the weight of said mixture, evidenced a greater bacteriostatic effectiveness than did either sodium pentachlorophenate or 3,4,4-trichlorocar-banilide when used singularly while it will also be noted that mixtures containing 95.0 weight percent sodium pentac'hlorophenate and 5.0 weight percent 3,4,4- tricholorcarbanilide evidenced substantially less bacteriostatic effectiveness than either 3,4,4'-trichl-orocarbanilide or sodium pentochlorophenate. Therefore, further tests were conducted to determine the point at which the mixture of this invention ceased to show synergism. The test results showed that mixtures of sodium pentachlorophenate and 3,4,4-trichlorooarbanilide ceased to be synergistically active when the weight percent of the sodium pentachlorophenate exceeded 93.0. Likewise, similar tests revealed that mixtures containing less than 58.0 weight percent of sodium pentachlorophenate were not synergistically active.

When examining the data, it must be remembered that, when talking in terms of percent light transmission, differences of even a fraction of one percent are very significant. Therefore, an increase of 1.4 percent as evidenced by the mixture consisting of 65.0 Weight percent sodium pentachlorophenate and 35.0 weight percent 3,4,4- trichlorocarbanilide indicates a decided decrease in amounts of live bacteria over either of the compounds comprising the mixture.

A major shortcoming of most germicides is that they dont have any lasting effect upon fabrics, For example, the spillage of water onto linen during use often results H in the dissipation of the germicidal agent. Therefore, to

evaluate the resistance to water of the germicidal mixture of this invention a series of tests was performed using two antimicrobial sour solutions. Solution 1 consisted of 0.0172 gram of zinc silicofluoride and 0.0038 gram of a mixture of sodium pentachlorophenate (C Cl ON,,) and 3,4,4-trichlorocarbanilide (C 9 3 2 dissolved in 100 cc. of distilled water. Solution 2 consisted of 0.0172 gram of zinc silicofluoride and 0.0023 gram of a mixture of sodium pentachlorophenate (C Cl ON and 3,4,4- tric'h'lorocarbanilide (C H Cl N O) dissolved in 100 cc. of distilled water. %-ll'1Ch square swatches of muslin were then treated with the antimicrobial sour solutions in a Launder-Ometer jar as described in Example 1. After having been treated with the antimicrobial sour, the swatches Were thoroughly rinsed in 3 liters of demineralized water and then added to a 13 mm. ID. test tube containing 10 cc. of FDA broth plus 1 drop of a 2'4-hour Staphylococcus aurcus, strain 209, broth culture. The test tube was then maintained at a temperature of F. for a 24-hour period and the bacteriostatic effectiveness determined as in Example I. The results of these tests are shown in the following table. For purposes of comparison, the percent light transmission through 10 cc. of broth culture untreated by the germicide is also included in Table 2. The percent light transmission is relative to the light transmission through uninoculated FDA broth.

The data in Table 2 reveals that the synergistic mixture of this invention left the fabric highly aseptic even after a thorough rinsing.

EXAMPLE 3 Many laundry sours and germicides used by the laundry industry have a disadvantage in that they tend to leave a residue on the wash load. This residue is undesirable, in that after several washings the fabrics become coarse and stiff. Therefore, tests were run on the synergistic mixture of this invention to determine its tendency towards such build-up. The tests consisted of contacting muslin swatches with the two antimicrobial sour solutions in a Launder-Ometer jar, as described in Example 1, and drying .the swatches. The swatches were then washed with a detergent and again contacted with the antimicrobial sour solutions. This process was repeated a total of five times. At the conclusion of the fifth washing, the swatches were added to FDA broth and Staphylococcus aureus bacteria as previously described in Example 2. Further tests were conducted in which the muslin swatches received a thorough rinsing in 3 liters of demineralized water after the fifth washing. The results of these tests, as listed in the following table, wherein the percent light transmission is relative to the light transmission through uninoculated FDA broth, show that there is no build-up of the antimicrobial sour on the fabric, and that the degree of effectiveness remains substantially constant regardless of the number of germicidal applications.

The prior tests as described and reported hereinabove were concerned with the bacteriostatic effectiveness of the synergistic mixture of this invention when fabric treated with said mixture was placed in a broth solution containing Staphylococcus aureus bacteria. Additional tests were then run in which the bacteria were placed directly on the fabric, In conducting these tests, A-inch square muslin swatches were treated with the two antimicrobial sour solutions in a Launder-Ometer jar as heretofore described. After the swatches were dry, /2 cc. of 24-hour Staphylococcus aurcus, strain 209, was added to the center of the muslin swatch. The swatches were then mounted atop a 50 cc. beaker and placed in a cabinet at 90 F. for 3 hours. The swatches were then removed from the cabinet and placed into a 13 mm. ID. test tube containing cc. of FDA broth having the same composition as heretofore described. The test tube was then maintained at a temperature of 90 F. for 24 hours. The bacteriostatic effectiveness of the antimicrobial sour was then measured by use of a K'lett-Summerson Photoelectric Colorimeter. Further tests were conducted in which the swatches were contacted five successive times with the antimicrobial sour solution. Between each of the five contacts the swatches were washed with a detergent. After the fifth contact the swatch was placed into FDA broth for 24 hours as described above, The results of these tests are reported as percent of light transmission through the Staphylococcus aureus-broth solution relative to the light transmission through uninoculated FDA broth.

It will be noted from the data in Table 4 that the synergistic mixture of this invention evidenced the same high degree of effectiveness against bacteria incubated directly on the fabric as that shown when the fabric was placed in an environment containing the bacteria.

In addition to the above tests, other tests were conducted in which the synergistic mixture of this invention was combined with other laundry sour compounds such as acetic acid, glycolic acid, oxalic acid, ammonium acid fluoride, ammonium silicofluoride, and sodium acid fluoride. The results of these tests revealed that the synergistic properties of the mixture of sodium pentachlorophenate and 3,4,4-trichlorocarba-nilide were evidenced equally as well with the above laundry sours as with zinc silicofiuoride, that is, the synergistic properties of a mixture of sodium pentac'hlorophenate and 3,4,4-trichlorocarbanilide are independent of the particular laundry sour compound with which it is combined.

While the above discussion and tests results have been concerned with the bacteriostatic effectiveness of the synergistic mixture of this invention, it should be pointed out that mixture is also synergistically active with regards to fungicidal effectiveness. In order to determine the fungicidal effectiveness, a number of tests were conducted in the following manner. A l flz-inch radius circular muslin swatch was treated with 100 cc. of antimicrobial sour solution, by contacting the swatch and the sour solution in a Launder-Ometer jar as hereinabove described. The sour solutions used corresponded to solutions 1 and 2 identified in Example 2. The treated swatch was then inoculated with 2 cc. of a water dispersion of Chaetomium globosum which had been grown on potato dextrose agar and the swatch then placed atop mineral salts agar which had been solidified in a Petri dish. The Petri dish was loosely covered and incubated at a temperature of F. for a period of 15 days. At the end of this period the swatch was removed from the Petri, rinsed under demineralized water and air dried :at 65% relative humidity and 70 F. for 24 hours. The swatch was then examined for visual evidence of mildew growth and then burst on a Mullen tester which determines fabric strength loss due to growth of the Chaetomium globosum on the fabric. The results of such tests showed an excellent correlation between visual growth of the Chaetomium globosam and loss of bursting strength and showed that the swatches treated with the synergistic mixture of this invention had a bursting strength of as much as 17 pounds per square inch higher than those swatches treated with only one of the compounds comprising the synergistic mixture,

EXAMPLE 5 This example illustrates an antimicrobial laundry sour composition which can be advantageously employed in commercial laundries. The weight percentages are based upon the weight of the antimicrobial laundry sour composition:

About 67% by weight of sodium silicofluoride, About 29% by Weight of sodium pentachlorophenate, About 4% by weight of 3,4,4'-trichlorocarbanilide.

It should be apparent that the objects of this invention have been realized. Namely, a germicidal composition has been discovered which is low in cost, readily available and which has excellent bacteriostatic and fungicidal properties.

We claim:

-1. An antimicrobial laundry sour composition consisting essentially of a laundry sour selected from the group consisting of acetic acid, glycolic acid, oxalic acid, ammonium acid fluoride, ammonium silicofiuoride, sodium acid fluoride, sodium silicofiuoride and zinc silicofluoride and a germicide, said germicide consisting of a synergistic mixture of 58 to 93 Weight percent, based on the Weight of said synergistic mixture, of sodium pentach-lorophenate and 42 to 7 Weight percent, based on the weight of said synergistic mixture, of 3,4,4-trichlorocarbanilide; furthermore, said germicide being present in the amount of from 10 to 60 weight percent of said antimicrobial laundry sour composition.

2. The composition of claim 1 wherein the laundry sour is zinc silicofluoride.

3. The composition of claim 1 wherein the laundry sour is sodium sil-icofiuoride.

4. An antimicrobial laundry sour composition comprising about 67 weight percent sodium silicofluoride,

References Cited by the Examiner UNITED STATES PATENTS 2,133,287 10/38 'Flett 260-512 2,463,761 3/49 Garverich 252136 2,846,398 8/58 Beaver et al 252106 2,925,361 2/60 Bollenback 16738.7 XR

OTHER REFERENCES Applied Microbiology, vol. 8, No, 1 (1960), article by Noel et al. (pages 1-4).

JULIUS GREENWALD, Primary Examiner. 

1. AN ANTIMICROBIAL LAUNDRDY SOUR COMPOSITION CONSISTING ESSENTIALLY OF A LAUNDRY SOUR SELECTED FROM THE GROUP CONSISTING OF ACETIC ACID, GLYCOLIC ACID, OXALIC ACID, AMMONIUM ACID FLUORIDE, AMMONIUM SILICOFLUORIDE, SODIUM ACID FLUORIDE, SODIUM SILICOFLUOORIDE AND ZINC SILICOFLUORIDE AND A GERMICIDE, SAID GERMICIDE CONSISTING OF A SYNERGISTIC MIXTURE OF 58 TO 93 WEIGHT PERCENT, BASED ON THE WEIGHT OF SAID SYNERGISTIC MIXTURE, OF SODIUM PENTACHLOROPHENATE AND 42 TO 7 WEIGHT PERCENT, BASED ON THE WEIGHT OF SAID SYNERGISTIC MIXTURE, OF 3,4,4''-TRICHLOROCARBANILIDE; FURTHERMORE, SAID GERMICIDE BEING PRESENT IN THE AMOUNT OF FROM 10 TO 60 WEIGHT PERCENT OF SAID ANTIMICORBIAL LAUNDRY SOUR COMPOSITION 